Faf du Plessis would not have been playing in this Test were it not for JP Duminy hurting his Achilles tendon at the Gabba. And just as Duminy did on debut in Perth four years ago, du Plessis has grabbed his first chance at Test cricket to provide a remarkable result for the South Africans. At the WACA it was a near-record chase of 414 for victory; this time South Africa's challenge was to bat for four and a half sessions on a wearing Adelaide Oval pitch to salvage a draw.

Thanks to du Plessis, they did so. Thanks to du Plessis, the scoreline remains at 0-0 heading into the decider in Perth, despite Australia having had the best of the first two Tests. And thanks to du Plessis, Australia's bowlers will have only four days to recover from some serious exhaustion, especially Peter Siddle, who sent down 63.5 overs for the match and was so debilitated by the time he bowled the final over of the match that he could barely stand up.

Of course, it wasn't all down to du Plessis. Early in the day, AB de Villiers played against type to score 33 from 220 balls without a boundary. Jacques Kallis again fought off his hamstring strain to provide important support in a 110-ball innings of 46. And Dale Steyn, Rory Kleinveldt and Morne Morkel did just enough to ensure that the No.11, Imran Tahir, would not be required. For South Africa, who will lose the No.1 Test ranking if Australia take the series, it was a draw that felt like a win.

For Michael Clarke and his men, it was an opportunity missed. There wasn't a lot more the Australians could have done, especially with James Pattinson's injury leaving them a bowler short throughout the fourth innings. But there were some half-chances that they were unable to take, the kind of tiny openings that on a day like this must not be wasted. An Australian victory was still possible until the final over of the last hour of the match.

By that stage, Siddle looked as if he'd just run a marathon. Somehow, he kept running in and his pace barely dropped, but Morkel was good enough to block out the over, which left South Africa on 8 for 248 when stumps was called. The score was irrelevant to the South Africans, who had given up on the chase of 430 on the fourth afternoon. Wickets were all that mattered. And a couple of breakthroughs in the final 40 minutes kept the contest alive.

Steyn fell for a 28-ball duck when he chipped an inswinging full toss from Siddle to midwicket, where Rob Quiney snapped up a sharp catch. And Kleinveldt survived for 17 deliveries before he missed a yorker and was bowled by Siddle for 3. In the end, Siddle finished with 4 for 65 from 33 overes, but his herculean effort was more than matched by du Plessis, who ended up unbeaten on 110 from 376 balls. For any batsman, it would have been a magnificent innings; for a debutant, it was preposterously good.

Most notable was the fact that du Plessis did not become overawed by the situation. He spent an eternity in the nineties but was not flustered, the team goal of survival overshadowing his own ambitions. When he eventually pushed two runs through cover off Ben Hilfenhaus and became the fourth South African to score a century on Test debut, after Andrew Hudson, Jacques Rudolph and Alviro Petersen, he acknowledged the applause and then settled straight back down to continue his job.

The milestone took him 310 deliveries, but he was far from stagnant. He played his shots when the opportunity arose and finished with 14 boundaries. He was as calm as Duminy had been back in 2008; in fact, his effort was much more impressive because the conditions were tougher and nobody else in the line-up managed so much as a half-century. The Australians thought they had du Plessis twice in the first session, only to be denied on review.

Both came off the bowling of Clarke, who drew positive lbw calls from Billy Bowden when du Plessis had 33 and again on 37. The first time, the batsman's review showed the ball had pitched a fraction outside leg stump; the second time it revealed that the two noises Bowden had heard were bat on ball and bat on ground - the ball had not even struck du Plessis on the foot or pad.

The Australians also used up their final review shortly before lunch when du Plessis, on 49, offered no shot to a Nathan Lyon delivery that pitched and struck him outside the line of off stump but was turning enough to interest Clarke. However, Eagle Eye suggested the ball would have bounced over the top of the stumps, and Clarke was left to consider how he would find six wickets in two sessions with no further reviews available.

In the last over before tea, they had a chance when du Plessis edged Hilfenhaus and Matthew Wade, standing up to the stumps, couldn't grasp the catch. Ed Cowan also put down a tough chance at short leg in the final session when Steyn clipped Siddle off his pads and the ball flew low to the ground, and they were the kind of opportunities the Australians couldn't afford to miss.

Cowan did complete a much easier catch in close when Lyon, who bowled 50 overs in the innings and 94 for the match, drew an inside edge onto pad from Kallis that popped up to short leg. Kallis had made 46 and given his injury, his effort was just as critical as that of du Plessis. De Villiers also played a key role until he was bowled by Siddle for a laborious 33 from 220 deliveries, an innings that did not include a boundary and was second only to Chris Tavare's effort at Madras in 1982 in terms of the lowest strike-rate for an innings of at least 30 runs in Test history.

De Villiers was happy defending and that was all South Africa really needed. They also required someone to stick around for the whole day, and du Plessis obliged. For the first time since 1921, Australia and South Africa had played out two consecutive draws. And for the second time this series, Australia saw a potential victory evade them. It all comes down to Perth.

Brydon Coverdale is an assistant editor at ESPNcricinfo. He tweets here